How Warm was the Roman Climate? – a brief survey of evidence for the Roman Warm Period

Garrett Ryan, “How Warm was the Roman Climate?” (Toldinstone, 23 February 2022)

In this instalment in his Toldinstone series on Youtube, Dr Garrett Ryan surveys evidence from dendrochronology (the study of tree rings) and other physical proxy phenomena that the Roman Empire experienced a long period of warm climate from the second century BCE to the second century CE known as the Roman Warm Period. The first part of this mini-documentary deals with the physical evidence that the late Roman Republic / early Roman Empire experienced warm summer temperatures in the Alpine region of about two degrees Celsius higher than they are today. Other physical evidence from places as far apart as Britain, Spain, Italy and southwest Turkey also suggest average annual temperatures of about two degrees Celsius higher than their current late 20th-century equivalents.

The second part of the mini-documentary emphasises that the Roman Warm Period was specific to the Mediterranean World and Europe, and that other parts of the world did not experience similar phenomena. The Roman Warm Period is thus not comparable with current global warming. The documentary concludes by looking at what impact the Roman Warm Period and its end might have had on Roman history and deducing that this climatic phenomenon and its aftermath had much less impact than might be assumed; while it is true that the Roman Warm Period could have allowed Hannibal to take his elephants over the Alps, and changing climate in Central Asia could have caused a long drought that forced nomadic Hunnic tribes there to travel across western Asia into Europe during the fifth century CE, the period’s warmth was neither uniform nor consistent across the empire’s territory and the empire’s final downfall was due to internal economic and social causes.

Illustrated with photographs and maps, the video is very informative though perhaps not quite as entertaining as others in the series – the topic doesn’t quite lend itself to a colourful roaming travelogue showing art, the ruins of formerly imposing and magnificent buildings or literature – and Dr Ryan’s narration seems more terse and less humorous. There is still much food for thought though, as to how the Roman Warm Period might have influenced the physical settings in which the dramas and events that made the Roman Empire what it was then and what it is to us today played out.